Comparison of pleasant and unpleasant smile characteristics in the perception of the laypeople in an Iranian population.

INTRODUCTION: This study aimed to compare the characteristics of pleasant and unpleasant smiles from the perception of laypeople. METHODS: Two-hundred posed smile photographs were obtained from adult participants with no anomaly, restoration, or severe crowding and spacing in anterior teeth. Photographs were shown to 26 judges to give each photograph a score for attractiveness. Upper and lower quartiles for the most and least rated smiles were determined, and variables including gingival display, smile arc, midline deviation, buccal corridor, smile width, tooth rotation or malposition, diastema, upper and lower vermilion show, and tooth form were measured. Independent-sample t test and Pearson chi-square analysis were used to determine the differences between the pleasant and unpleasant groups for quantitative and qualitative variables, respectively. The linear regression model revealed variables with the most significant impact on the mean score. RESULTS: All quantitative and qualitative variables except tooth form significantly differed between pleasant and unpleasant smile groups (P <0.05). The consonant smile arc was associated with an increase of 12.59% in mean scores compared with the inconsonant smile arc. Each tooth reported with malposition was correlated with a decrease of 9.37% in the scores. In the same way, each 1-mm increase in midline diastema and occlusal cant coincided with a drop of 8.73% and 3.59% in scores, respectively. CONCLUSIONS: The results of this study suggested that smile arc, tooth malposition, midline diastema, and occlusal plane canting had the most impact on smile esthetics and should be given priority by orthodontists in the treatment plan of choice.

Dental stem cell banking: Techniques and protocols.

Dental tissue-derived stem cells (DSCs) provide an easy, accessible, relatively noninvasive promising source of adult stem cells (ASCs), which brought encouraging prospective for their clinical applications. DSCs provide a perfect opportunity to apply for a patient's own ASC, which poses a low risk of immune rejection. However, problems associated with the long-term culture of stem cells, including loss of proliferation and differentiation capacities, senescence, genetic instability, and the possibility of microbial contamination, make cell banking necessary. With the rapid development of advanced cryopreservation technology, various international DSC banks have been established for both research and clinical applications around the world. However, few studies have been published that provide step-by-step guidance on DSCs isolation and banking methods. The purpose of this review is to present protocols and technical details for all steps of cryopreserved DSCs, from donor selection, isolation, cryopreservation, to characterization and quality control. Here, the emphasis is on presenting practical principles in accordance with the available valid guidelines.

Prioritized Commitment-Based Clinical Assessment: A New Method for Assessment of Orthodontic Treatment Outcomes.

OBJECTIVE: Quality assessment is an essential part of orthodontic treatment. Most of the current indices are essentially based on occlusal assessment. However, an ideal occlusion is only one aspect of an ideal treatment. The aim of this article is to introduce a new prioritized commitment-based clinical assessment (PCCA) method and present its reliability and linear correlation test in comparison with the comprehensive clinical outcome assessment (CCA). METHODS: One hundred treated cases were scored with the conventional assessment tool--the CCA--and the newly developed assessment tool--the PCCA--with 2 calibrated examiners at 2 different time intervals. These cases were randomly selected including equal numbers of the main malocclusions managed with fixed conventional edgewise appliances within the past 3 years and had complete pre-treatment and post-treatment routine records. The intraclass correlation coefficient (ICC) was used to assess the intra- examiner repeatability of the total scores of both methods. Pearson's correlation coefficients were computed to assess the linear relationships between the CCA and PCCA scores. RESULTS: The intra-examiner reliability assessed for CCA and PCCA showed high repeatability for both examiners (ICC: 0.93 and 0.945, respectively). The inter-examiner reliability values for CCA and PCCA, assessed by ICC, were 0.84 and 0.96, respectively. The linear correlation between the 2 methods, assessed by comparing the mean score of each case by the 2 examiners was significant, at 0.01. CONCLUSION: The PCCA method can be used for quality assessment in treated orthodontic patients. The preliminary test of the new method presented good inter- and intra-observer agreements and a significant linear correlation with the CCA method.

A doubly-inflated Poisson regression for correlated count data.

Count data have emerged in many applied research areas. In recent years, there has been a considerable interest in models for count data. In modelling such data, it is common to face a large frequency of zeroes. The data are regarded as zero-inflated when the frequency of observed zeroes is larger than what is expected from a theoretical distribution such as Poisson distribution, as a standard model for analysing count data. Data analysis, using the simple Poisson model, may lead to over-dispersion. Several classes of different mixture models were proposed for handling zero-inflated data. But they do not apply to cases when inflated counts happen at some other points, in addition to zero. In these cases, a doubly-inflated Poisson model has been suggested which only be used for cross-sectional data and cannot consider correlations between observations. However, correlated count data have a large application, especially in the health and medical fields. The present study aims to introduce a Doubly-Inflated Poisson models with random effect for correlated doubly-inflated data. Then, the best performance of the proposed method is shown via different simulation scenarios. Finally, the proposed model is applied to a dental study.

How to Predict Difficult Tracheal Intubation: The Application of Acromio-axillo-suprasternal Notch Index.

BACKGROUND: The incidence of difficult laryngoscopy or tracheal intubation is high, which needs a method to predict the difficulty of tracheal intubation to decrease the rate of complications. Therefore, the aim of this study was to evaluate acromio-axillo-suprasternal notch index (AASI) method for predicting difficult tracheal intubation and difficult laryngoscopy. MATERIALS AND METHODS: This cross-sectional and diagnostic value study was performed on 108 patients who had indication for endotracheal intubation in the emergency department. Before endotracheal intubation, AASI was evaluated in all patients. The sensitivity, specificity, and total accuracy for predicting the power of AASI for the difficulty of tracheal intubation were measured. RESULTS: Based on Cormack and Lehane grading system, 54 patients had easy endotracheal intubation (33.3% Grade I and 66.6% Grade II) and 52 patients had difficult endotracheal intubation (57.7% Grade III and 32.7% Grade IV). The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy for AASI in cutoff point 0.515 for predicting difficulty of endotracheal intubation with 0.857 area under the receiver operating characteristic curve were 84.6%, 77.7%, 78.5%, 84%, and 81.13%, respectively. CONCLUSIONS: Our results showed that predicting difficulty of endotracheal intubation by AASI is accurate and with high sensitivity and specificity values, therefore, training this method to emergency physicians should be considered in our country or other countries. Further studies are required to confirm our findings.

Correlation between cervical vertebral maturation and chronological age in a group of Iranian females.

BACKGROUND: Correlation between chronological age at different stages of cervical vertebral maturation (CVM) is important in clinical orthodontic practice. The objective of this study was to evaluate the correlation between CVM stage and chronological age in a group of Iranian female patients. MATERIALS AND METHODS: This study was conducted on 196 digital lateral cephalometry of female patients with the age ranged 9-14 years. The CVM stage was determined with two calibrated examiners, using the method developed by Baccetti and its correlation with mean chronological age was assessed by the Spearman rank-order. The intra and inter-agreements were evaluated by weighted Kappa statistics in overall diagnosis of stages, in addition to determination of presence or absent of concavities at the lower border of second, third and fourth cervical vertebrae and the shapes of the third and fourth vertebrae. P < 0.05 was considered as significant. RESULTS: The correlation coefficient between CVM stages and chronological age was relatively low (r = 0.62). The least amount of inter-observer agreement was determined to be at the clinical decision of the shape of the fourth vertebra. CONCLUSION: Regarding the low reported correlation, the concomitant usage of other skeletal indicators seems necessary for precise determination of physiological age of the patients.

Acid and Alkaline Phosphatase Levels in GCF during Orthodontic Tooth Movement.

STATEMENT OF THE PROBLEM: The present constituents of gingival crevicular fluid (GCF) can reflect the changes occurring in underlying tissues. Considering variety of biologic bone markers, alkaline phosphatase and acid phosphatase have been examined as bone turn over markers in orthodontic tooth movement. PURPOSE: The current study designed in a longitudinal pattern to determine the changes of acid and alkaline phosphatase (ACP & ALP) in GCF during orthodontic tooth movement. MATERIALS AND METHOD: An upper canines from twelve patients (mean age: 14±2 years) undergoing extraction orthodontic treatment for distal movement served as the test tooth (DC), and its contralateral (CC) and antagonist (AC) canines were used as controls. The CC was included in orthodontic appliance without orthodontic force; the AC was free from any orthodontic appliance. The GCF around the experimental teeth was harvested from mesial and distal tooth sites immediately before appliance placement (T0), and 14 (T2) and 28 days (T3) after it and ALP and ACP concentration were determined spectrophotometrically. RESULTS: ALP concentration was elevated significantly in DC and CC groups at days 14 and 28 compared with the AC. In DC group, the ALP was significantly greater in mesial sites than distal site, while no significant changes were found between both sites of CC. The peak level of ALP was observed in mesial sites of DC at T2. Regarding ACP, significant elevation of this enzyme was seen in DC group both in mesial and distal sites at T2 and T3. The peak level of this enzyme was seen at T2. CONCLUSION: Monitoring simultaneous changes of ALP and ACP levels in GCF can reflect the tissue responses occur in periodontium during bone formation and bone resorption during orthodontic tooth movement, respectively.

Mini-Screw Supported Intrusion Mechanics Used For Open Bite Closure and Facial Improvement: A Case Report.

Open-bite is one of the most challenging malocclusions to be corrected orthodontically. Temporary anchorage devices had enabled orthodontists to treat open-bite cases successfully. In this case report a 15 years old girl with open-bite was treated with maxillary molar intrusion with the aid of alveolar mini-screws.

Distraction osteogenesis for cleft palate closure: A finite element analysis.

BACKGROUND: Current methods of closure of the cleft palate result in the formation of scars and impairment of growth. Distraction osteogenesis (DO) might be an effective means to repair or at least reduce the size of wide clefts. This study investigates the biomechanical aspects of this process. MATERIALS AND METHODS: DO simulation was applied to reduce the size of a unilateral hard palate cleft on a three-dimensional (3D) model of the maxilla. For the position of osteotomy lines, two different models were assumed, with the osteotomy line on the affected side in model A and on the intact side in model B. In each model, DO screws were placed on two different positions, anteriorly (models A1 and B1) and posteriorly (models A2 and B2). Displacement pattern of the bony island in each of the four models, reaction forces at DO locations, and von Mises stress were estimated. Mesh generation and data processing were carried out in the 3D finite element analysis package (ABAQUS V6.7-1; Simulia Corp., Providence, RI, USA). RESULTS: In model B2, the island moved almost evenly, assuring a more complete closure of the cleft. The most uniform stress distribution was found in model B1. CONCLUSION: The results suggest that the best positions for the DO screw and the osteotomy line for closure of the cleft palate are posteriorly and on the intact side, respectively.

Effects of flapless bur decortications on movement velocity of dogs' teeth.

BACKGROUND: Different surgical procedures that reduce orthodontic treatment time have been recommended. The aim of this study was to evaluate the effectiveness of a new less invasive surgical technique (called flapless bur decortications) for accelerating orthodontic tooth movement. MATERIALS AND METHODS: This study was designed as a split-mouth study. The left and right maxillary first premolars of five dogs were extracted. An A-NiTi closed coil spring and an absolute anchorage was used for premolar protraction in both sides. In each dog, decortications were performed for one side and the other side was used as the control group. The distance between canine and second premolar was measured and the sites of decortication were evaluated histologically. The data was analyzed by paired samples t-test and multivariate analysis of two-way repeated measures ANOVA. RESULTS: The study teeth moved more than their controls in the first month and less than their controls in the third month (P < 0.05). The total difference between study and control movements was not significant (P < 0.05). CONCLUSION: (1) Corticotomy facilitated orthodontic tooth movement is achievable with flapless bur decortication technique. (2) Velocity of tooth movement decreases in later stages of treatment due to maturation of newly formed bone at decortication sites.

Orthodontic treatment need in 14-16 year-old Tehran high school students.

AIM: To assess orthodontic treatment need in a Tehran high school population. METHODS: The Dental Health Component (DHC) of the Index of Orthodontic Treatment Need (IOTN) was used by 21 trained examiners to estimate the orthodontic treatment need in 5200 Tehran high school students. The children, between 14 and 16 years of age, attended 84 high schools in 21 educational areas in Tehran and the neighbouring city of Rey. Children who had had orthodontic treatment and those who had not been treated were assessed. Children under treatment were excluded. Major components of the DHC were recorded. RESULTS: When the DHC is considered, 2 per cent of Tehran school children showed 'Extreme need', 18 per cent 'Severe need', 23 per cent 'Moderate need', 37 per cent 'Little need' and 20 per cent had 'No need' of orthodontic treatment. In those needing treatment (Grades 4 and 5) common deviations were hypodontia, contact point displacements, crossbites and increased overjet. A small number of the subjects (N=36) who had received orthodontic treatment required further treatment. Of these, 18 subjects (50 per cent) had hypodontia, 10 subjects (28 per cent) had contact point displacements and 4 subjects (11 per cent) had increased overjet. CONCLUSION: Twenty per cent of Tehran high school students needed orthodontic treatment (IOTN Grades 4 and 5).

Effects of low-level He-Ne laser irradiation on the gene expression of IL-1beta, TNF-alpha, IFN-gamma, TGF-beta, bFGF, and PDGF in rat's gingiva.

Biostimulatory effects of laser irradiation on cell proliferation and wound healing has been reported. However, little is known about the molecular basis of the mechanism. Interleukin 1beta (IL-1beta), tumor necrotic factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) play an important role in inflammation, while platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-beta) and blood-derived fibroblast growth factor (bFGF) are the most important growth factors of periodontal tissues. The aim of this study was to investigate the effect of low-level He-Ne laser on the gene expression of these mediators in rats' gingiva and mucosal tissues. Twenty male Wistar rats were randomly assigned into four groups (A(24), A(48), B(24), B(48)) in which A(24) and A(48) were cases and B(24), B(48) were controls. An incision was made on gingiva and mucosa of the labial surface of the rats' mandibular incisors. Group A(24) was irradiated twice with 24 hours interval, while the inflamed tissues of group A(48) was irradiated three times with continuous He-Ne laser (632.8 nm) at a dose of 7.5 J/cm2 for 300 s. An energy of 5.1 J was given to the 68 mm(2) irradiation zone. Rats were killed 30 min after the last irradiation of case and control groups, then excisional biopsy was performed. Gene expression of the cytokines was measured using reverse transcriptase-polymerase chain reaction (RT-PCR) technique. Results were analyzed with Kruskal-Wallis and Mann-Whitney U tests. The gene expression of IL-1beta and IFN-gamma was significantly inhibited in the test groups (P < 0.05), while the gene expression of PDGF and TGF-beta were significantly increased (P < 0.05). The case and control groups did not have a significant difference in the gene expression of TNF-alpha and bFGF (P > 0.05). These findings suggest that low-level He-Ne laser irradiation decreases the amount of inflammation and accelerates the wound healing process by changing the expression of genes responsible for the production of inflammatory cytokines.